1. Field of the Invention
The invention relates to a vacuum-assisted holding tool, and in particular to a device for holding a contact lens against a rotating cutting or polishing surface, and which permits spinning of the lens during the grinding or polishing operation.
2. Description of the Prior Art
Traditionally, hard contact lenses are modified to a desired contour in grinding, or polishing, by adhering the lens blank with double-sided adhesive tape to a spinning tool to be held against a rotating cutting or polishing surface, or lap. The application and removal of the double-sided adhesive are both time consuming, an frequently produce undesirable surface scratches in the lens.
Various attempts have been made to secure the lens by means of electrically induced suction, but these have been only marginally successful, inasmuch as, when adequate suction was achieved to securely hold the lens and to withstand stresses induced during grinding or polishing, frequently the lens would either break or warp during the process.